Deprecation warning when using regexp operator in where clause

[joshdaugherty]

Bug description

When I use the regex operator in a where clause...

$query->where('foo', 'regexp', '^bar$');

... I get the following log warning:

LOG.warning: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in ...statamic\cms\src\Query\Builder.php on line 702

The error is likely caused by some entries not having the 'foo' field/column, resulting in a null value being passed to the preg_match function.

It seems like the work from this v3.3.12 commit could be extended to the filterTestLikeRegex() function in cms/src/Query
/Builder.php: 1cde722.

Current:

    protected function filterTestLikeRegex($item, $pattern)
    {
        return preg_match("/{$pattern}/im", $item);
    }

Proposed:

    protected function filterTestLikeRegex($item, $pattern)
    {
        return preg_match("/{$pattern}/im", (string) $item);
    }

How to reproduce

1. Create at least one Entry with a value for a given field (e.g., handle: 'foo').
2. Create at least one separate Entry with no value for the same field from step 1.
3. Create a query scope using the where method; with the field handle from steps 1 and 2 in the first argument; and using the regexp operator in a where method (e.g., $query->where('foo', 'regexp', '^bar$');
4. Apply that query scope to an Entries field, configuring that field to allow it to select from the collection of the entries from steps 1 and 2.
5. Edit an entry/tag/etc. (or create a new one) that uses the field from step 4.
6. While editing the entry/tag/etc. from step 5, check the debug bar messages for the field from step 4 and presumably see LOG.warning: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in ...statamic\cms\src\Query\Builder.php on line 702

Logs

No response

Environment

Environment
Application Name: UAMS Statamic Sandbox
Laravel Version: 11.35.0
PHP Version: 8.2.26
Composer Version: 2.8.3
Environment: local
Debug Mode: ENABLED
URL: uams-statamic-sandbox.test
Maintenance Mode: OFF
Timezone: America/Chicago
Locale: en

Cache
Config: NOT CACHED
Events: NOT CACHED
Routes: NOT CACHED
Views: CACHED

Drivers
Broadcasting: log
Cache: file
Database: sqlite
Logs: stack / single
Mail: smtp
Queue: sync
Session: file

Statamic
Addons: 7
Sites: 1
Stache Watcher: Enabled (auto)
Static Caching: Disabled
Version: 5.42.1 PRO

Statamic Addons
jacksleight/statamic-bard-mutator: 3.0.3
statamic/importer: 1.5.1
statamic/ssg: 3.1.0
studio1902/statamic-peak-browser-appearance: 3.6.0
studio1902/statamic-peak-commands: 8.12.0
studio1902/statamic-peak-seo: 8.18.0
studio1902/statamic-peak-tools: 6.6.0

Installation

Starter Kit using via CLI

Additional details

No response